/*
 * Copyright (C) 2005-2011 MaNGOS <http://www.getmangos.com/>
 *
 * Copyright (C) 2008-2011 Trinity <http://www.trinitycore.org/>
 *
 * Copyright (C) 2010-2011 ProjectSkyfire <http://www.projectskyfire.org/>
 * 
 * Copyright (C) 2011 ArkCORE <http://www.arkania.net/>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#ifndef _REFERENCE_H
#define _REFERENCE_H

#include "Dynamic/LinkedList.h"

//=====================================================

template<class TO, class FROM> class Reference: public LinkedListElement {
private:
	TO* iRefTo;
	FROM* iRefFrom;
protected:
	// Tell our refTo (target) object that we have a link
	virtual void targetObjectBuildLink() = 0;

	// Tell our refTo (taget) object, that the link is cut
	virtual void targetObjectDestroyLink() = 0;

	// Tell our refFrom (source) object, that the link is cut (Target destroyed)
	virtual void sourceObjectDestroyLink() = 0;
public:
	Reference() {
		iRefTo = NULL;
		iRefFrom = NULL;
	}
	virtual ~Reference() {
	}

	// Create new link
	void link(TO* toObj, FROM* fromObj) {
		assert(fromObj); // fromObj MUST not be NULL
		if (isValid())
			unlink();
		if (toObj != NULL) {
			iRefTo = toObj;
			iRefFrom = fromObj;
			targetObjectBuildLink();
		}
	}

	// We don't need the reference anymore. Call comes from the refFrom object
	// Tell our refTo object, that the link is cut
	void unlink() {
		if (isValid()) {
			targetObjectDestroyLink();
		}
		delink();
		iRefTo = NULL;
		iRefFrom = NULL;
	}

	// Link is invalid due to destruction of referenced target object. Call comes from the refTo object
	// Tell our refFrom object, that the link is cut
	void invalidate() // the iRefFrom MUST remain!!
	{
		sourceObjectDestroyLink();
		delink();
		iRefTo = NULL;
	}

	bool isValid() const // Only check the iRefTo
	{
		return iRefTo != NULL;
	}

	Reference<TO, FROM> * next() {
		return ((Reference<TO, FROM> *) LinkedListElement::next());
	}
	Reference<TO, FROM> const * next() const {
		return ((Reference<TO, FROM> const *) LinkedListElement::next());
	}
	Reference<TO, FROM> * prev() {
		return ((Reference<TO, FROM> *) LinkedListElement::prev());
	}
	Reference<TO, FROM> const * prev() const {
		return ((Reference<TO, FROM> const *) LinkedListElement::prev());
	}

	Reference<TO, FROM> * nocheck_next() {
		return ((Reference<TO, FROM> *) LinkedListElement::nocheck_next());
	}
	Reference<TO, FROM> const * nocheck_next() const {
		return ((Reference<TO, FROM> const *) LinkedListElement::nocheck_next());
	}
	Reference<TO, FROM> * nocheck_prev() {
		return ((Reference<TO, FROM> *) LinkedListElement::nocheck_prev());
	}
	Reference<TO, FROM> const * nocheck_prev() const {
		return ((Reference<TO, FROM> const *) LinkedListElement::nocheck_prev());
	}

	TO* operator ->() const {
		return iRefTo;
	}
	TO* getTarget() const {
		return iRefTo;
	}

	FROM* getSource() const {
		return iRefFrom;
	}
};

//=====================================================
#endif
